US2567205A - Precipitation static reducing aircraft antenna - Google Patents

Description

P 1951 w. c. HALL 2,567,205

PRECIPITATION STATIC REDUCING AIRCRAFT ANTENNA Filed Oct. 7, 1947 FIG. 2

WAYNE a. HALL components previously Patented Sept. 11, 1951 PRECIPITATION STATIC REDUCING AIRCRAFT ANTENNA Wayne 0. Hall, Cheverly, Md., assignor to Fredric Flader, Inc., North Tonavvanda, N. Y., a corporation of New York Application October 7, 1947, Serial No. 778,450 8 Claims. (Cl. 2 50 33) (Granted under the act of March' 3, 1883, as

This invention relates to radio communication iniaircraft and is particularly directed to reception on long wire antennas. Such antennas are normally positioned between a forward mast and the vertical stabilizer.

; As has been long appreciated, under severe weather conditions rendering radio communication for navigational purposes absolutely necessary. radio contact frequently fails. Aviation history is replete with crashes under such conditions, many of which have been attributable directly to radio failure.

i Many attempts have been madeto avoid such failures. Shielded loops have been used. The potential metal surface aircraft has been discharged by fine wire dischargers, fluid droplet dischargers, and exhaust gas ionization. some of; these procedures have extended the range of weather conditions under which communication could be maintained, but the improvement has been insufficient under extreme conditions which ma be encountered, and has been ineffective with respect to long wire antennas.

I have discovered that static interference on long wire antennas may be'reduced sufllciently to render the receiver operative under conditions far past the threshold of inoperativeness under previous systems. My system may include in art known. Aircraft dischargers to control the plane potential may be used, particularly those described in my applications Serial Numbers 469,606, 518,692, now Patents 2,466,024 and 2,466,311, respectively, granted April 5. 1949, and 726,194 now abandoned. Surface insulation, previously used in connection with other types of antennas, may be employed. Such measures, however, are ineffective in ob' taining full efliciency of reception on long wire antennas.

7 According to m invention, not only must be enclosed in an insulating sheath, but this insulation may not be limited to the antenna alone. It must, in dielectric continuity, extend from the antenna over the strain insulators themselves, over spring tension units if employed, and over proximate supporting'tension wires or other conductive structures adiacent the antenna. It may extend in dielectric continuity to theaerodynamic surface of the air-f craft itself, and preferably does so. p (The present invention was madedurlng an initial survey of the problem of interference to a ir craft'reception. That survey subsequently de veloped into a comprehensive study of the physics of the charging and discharging of airborne the entire antenna amended April 30, 1928; 370 0.- G. 757) craft, and of the radio interference generated by these processes. Papers relating to this project may be referred to Proc. I. R. E. vol. 34, pp. 156, 161, 167, and 234. In the course of this study, the operation and effectiveness of the instant invention became more apparent.

The operation of the receiving systems of the present invention is effective in controlling corona discharge from the aircraft with particular respect to the antenna system. Corona from the antenna itself instantly blocks the receiver and must be prevented by suitable insulating material. The insulation enclosing the supporting conductive structures prevents corona from closely adjacent locations affecting the antenna. Consequently, the shock excitation previously encountered by discharges from the antenna sup porting structure are avoided.

In case the strain insulators are connected to uninsulated supporting wiresjas is conventional, to effect complete protection insulating tape may be wrapped around the wire and then over the insulator itself. In case insulated wire is used, looped about the insulator and wrapped on itself, the end of the wire must be protected Where the conductor would be exposed. In the latter case, the insulating sheath need not enclose the insulator. Thick insulating tape, such as rubber electricians tape, or othe similar tapes described below, covering the exposed end and extended to both sides thereof along the length of the sup porting system, would be suflicient.

Under previous systems, the antenna was conventionally coupled to an input circuit which was conductively connected with the planes metallic structure. The antenna itself was carried by attachment to the strain insulator, whose other end was supported bya rounded bracket or conductive structure. Evenif the antenna itself were wholly sheathed, the insulator and supporting structure would discharge by corona. Surface conductivity of the insulator is believed to play a part in this process. The short leakage path permitted th insulator to build up to the high corona potential required by its large radius of curvature, and to generate a high energy dis charge pulse. This is effectively prevented by the long leakage pathspresent in the instant invention. I

Since corona is prevented from occurring'adjacent the antenna, the remaining local interfinance is generated by more remote structures of the plane. Corona at such points is preferably to be eliminated by-limitingthe potential dif- 4. The system is of particular utility when used in combination with an aircraft employing resistive wick dischargers attached to the Wing tip and -stabilizer. surfaces, These dischargers are further described in myapplication'sertal Numbers 469,606, 518,692 and 726,194, of which this is a continuation in part.

The aircraft I of Fig. l is of conventional metal construction. The horizontal antenna II is supported between mast l2 and stabilizer l3. Two insulator units [4 and one tension device I! are shown. The tension member I5 is connected to bracket IS on the stabilizer. Lead I1 is taken into the interior of the plane by feed-through in! sulator l8. The antenna where used for receiving is preferably Joy-passed "to ground for low frequency signals, as shown, by an input circuit such as 2 I..

The. connecting sections 22-44 supporting antenna I I are metallic wire.

The insulating enclosure for the system is shown in detailed Figures 2 and 3. As explained above, not only must corona discharge be prevented from the antenna itself, but also from the associated supporting structure. To this end all metal parts of the system are wrapped with an adhesive insulating tape to form a continuous sheath thereover. While a number of thicknesses may be obtained by wrapping one piece on itself in overlapping relation, the sheath maybe applied in two layers with the second overlying the seam of the first. Insulating varnishes may also. be used, but preferably in conjunction with tape to provide an adequate protective thickness. Since potential differences between the aircraft and the atmosphere may be of the order of hundreds. of kiloyolts, a single coating of conventional insulating varnish would be practically useless.

Suitable insulatin tapes may be of rubber or, particularly, polyethylene resin. Other insulating substances may be used, and the sheath may be formed otherwise than by coating or adhesive attachment. As shown in Fig. 2, the insulating tape is Wrapped over the entire antenna ll, lead in H, and feed-through insulator I8. For the purposes of illustration, transparent insulation has been shown.

The insulation is carried continuously over the end of antenna wire II at its attachment to insulator M to enclose the metal present. Preferably the ceramic material of the insulator is insulated also, and supporting guy 24 is sheathed to mast 12. The latter is wholly insulated down to its base at the aerodynamic surface of the aircraft.

The antenna sheath is carried over'nea'r insulator I 4, guy 23, tension unit l5 and guy 2.2 to bracket I 6. The latter is Wrapped down'to its base at the stabilizer I3. I Thus there is no exposed metallic surface on the antenna or on its supportingstructure.

*Fig. 3 shows in detail a portion of the sheath applied to guy 23 and insulator M. An inner layer of transparent tape25 is wrapped over the wire and insulator, its edges in abutting relation. A- second layer 26 is then applied, overlying the seam in the first layer.

' 'The, system thus provided is protected from shock excitation by corona discharge from the antenna and, its supportin stru ur 1'5v antenna system comprising, a conductive linear The invention described herein may be manufactured' and used by or for the Government of the United States of America for governmental purposes, without the payment of any royalties thereon or therefor.

What is; claimed is:

1. In combination with an aircraft having conductive aerodynamic surfaces, an aircraft antenna member, means supporting said antenna member at itsends in spaced and insulated relation to said aircraft including an insulator and means connecting said insulator to said aircraft, and an. insulating shea h: wh nclos ns. m antenna and-saidsupporting meansand. extend ing in dielectric-.continuity=-to the, aerodynamic surfaces ofv'said. aircraft.

2. In combination with an; aircraft. haying conductive aerodynamic surfaces, an aircraft antenna $S B 0 P ing av longitudinal wire antenna. an insulator ateach end thereof. two lengths. f s p n w re eah.connect one endto one of said insu1ators..andat. the other-end te-said aircraft, for supporting said antenna under tension in spaced, and insulated relation-tasaicgaircraft, and an insulating sheath wholly enclosing said antenna, .saidinsulator; and saidsupporting. wires. extending electric continuity toe-the aerodynamicsurfaces ofsaid aircraft. 3... In combination withannaircraft conductive aerodynamic surfaces, an aircraft antenna system comprisinga. ma t pmiectma from saidaircraft, afirst. suppo t ne Wire: QQIB nected atone. end to said mast, a firstinsulator connected to the-other end of said supporting Wire.v a. longitudinal, wire. antenna connected at ne M s d fir t-r n l mae ond. nfill: lato connected t.0"1' h8 1 h. 17mend ofi Saidan: tenna, asecond. supp rting. wire c nn ted.

tween -saidpsecond insulator andsaid, aircraft.

a: lead-in wire connected, to. saidantennaiand extending therefrom through. the aerodynamic suriaee t aid ai r ft nd a insulating. sheath.

wholly enclosing said antenna, said. insulatora. said, supporting wires and. said lead-in wire,. and extendingin dielectric continuity to the aerodynamic surtaces-ofsaidaircraft. a 4.!Lhecombination. claimed in claim 1. wherein. said. sheath. comprises at least one layer of: insulating tape, wrapped dielectric. conI-I tinuity upon said antenna and said supporting.

5.;.The-.=combination. as. claimed in claimnl. wherein. said sheath ,is' composed of. polyethylene. 6. In. combinationwith an, aircraft having conductiyewaerodynamic, surfaces; and an! na mau din sn cedi ela ion ther to. means for preventing. discharge from said, antenna. compr naaa insula n shea h. w l encl sing s id finn rl n im fdr d h r in aid aircraft atfother point's comprising a mnl,tipllig';,- ity 0f fine, filer disch g no ta-ek tr aa hi sen: nested, to. said conductive. aerodynamic. surf In combinationiwith an aircraft... having cQnduetiveaerodynamic. s f d an tenna. wit m ans. suepnr ine. aid. in spaeed, relation to. said conductive. surfaces,

electrodes electrically connected to said conductive aerodynamic surfaces in regions of high electrical field, said electrodes including a fibrous material having a multiplicity of free surface fibers each affording a conductive path of microscopic cross-section.

8. In combination with an aircraft having conductive aerodynamic surfaces and an antenna with means supporting said antenna in spaced relation to said conductive surfaces, means for preventing discharge from said antenna comprising an insulating sheath wholly enclosing said antenna and said supporting means and extending in dielectric continuity to said aerodynamic surfaces, and means for discharging said aircraft comprising a plurality of electrodes electrically connected to said conductive aerodynamic surfaces in regions of high electrical field, said electrodes each comprising an exposed mass of normally non-conductive fibrous material having myriad projecting fibers with free ends having radii of curvature of microscopic order, said fibers carrying highly resistive films of conductive material, which films have in the area of said free ends a thickness of microscopic order.

WAYNE C. HALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,743,078 Mirick' Jan. 7, 1930 1,962,202 Meredith June 12, 1934 2,136,532 West Nov. 15, 1938 2,282,402 Hefele May 12, 1942 2,316,623 Van B. Roberts Apr. 13, 1943 2,320,146 Leake May 25, 1943 2,357,738 Yoder Sept. 5, 1944 2,373,660 Closson Apr. 17, 1945 2,416,280 Bennett Feb. 25, 1947 2,418,961 Wehner Apr. 15, 1947 OTHER REFERENCES Proceedings of the IRE, May 1939, by H. Hucke, pages 301-316.

Beach: What of Air Safety?; Electrical Engineering, May 1948, pages 423-429.

Images